Method and means for the identification of electrical cables



June 14,1927. 1,632,030

w. H. MARTIN METHOD AND MEANS FOR THE IDENTIFICATION OF ELECTRICAL CABLES Filed Sept. 26. 1922 IN V EN TOR.

k Mom form a pair.

there are 35 white pairs anda so-called "tracer pair, having and terminating of particular pairs 40 greatly facilitated by such a color code. In

Patented June 14, 1927.

UNITED STATES I I 1,632,030 PATENT OFFICE.

WILLILI H. MARTIN, .01 OHAPPAQUA, NEW YORK, ASSIGNOR '10 Amman mn- PHONE AND'TELEGBAPE comm, A CORPORATION OI m YORK- II'IHOD MEANS FOR THE IDEITIFICATION OI'ILEGIBIGL'L GABLES.

Application fled semina ac, ma. Serial in. 500,144.

used 1n the manufacture of such cables in order to insure greater accuracy, and therefore efiiciency, in the manufacture and installation of such cables.

The telephone cables of any of the wellknown ty es usuall consist of at plurality of airs o insulate conductors stranded tot er in order to form a com act core. ach conductor of such a cable is covered with paper insulation usually in the form of a tape spirally applied in such' manner that each successlve convolution overlaps partly the preceding one. Two conductors thus insulated, but usually difiering in the color of the insulating aper, are twisted together to e use of a different color of insulation upon each conductor of a pair ofwires was found desirable in order to distinguish the two sides of the pair du'rin the processes of manufacturing and of msta- 1mg the cables containing these conductors.

With the increase in the number of pairs contained in such cables, especially exchange cables which are intended for subscribers distribution purposes, it became increasingly difiicult to select certain pairs therein licing and terminating, so that this led to the adoption of a group color system. Thus, for examp in a 101 pair exchange cable le fifty red-white pairs, fifty blueing some distinctive color combination. The pairs of each of these groups have defin te numbers assigned to them, so that the spliclarger cables a greater number of groups are employed, the pairs in each group having the same combination of colors of insulatiofi, while the color combination of the different groups varies.

In the manufacture of these so-called exchange cables (as distinguished from toll cables, which have different color combinations), the pairs of wires are laidup in layers which vary in number depending upon the size of the cable. These layers are twisted around a central core, consisting of a few pairs of wires, the adjacent layers be- ,ing twisted in opposite directions. If the an adjacent pairs in any layer have the same of twist, confusion is likel length of twist, it will be seen that aparal-v lehsm exists between the conductors of the said palrs, so that that form ofinductive interference known as cross-talk will result. It has accordingl been proposed to make up these cables with the adjacent pairs having different lengths of twist. Thus for example, ared-white pair of X inches twist would be flanked on each side b other redwhite pairs of Y inches twist. imilarly, in other groups of'the same cable, as for example, the blue-white group, a blue-white pair of X inches twist would be placed ad- Jacent to similarly colored pairs of Y inches twist.

It will be apparent from the foregoing descr1 tion that, since such a cable is composed of like colored pairs having difi'erent lengths less some means he rovide to readily distlnguish the pairs o difierent twists. This need for. a suitable distinguishing mark arises in the storerooms where the spools of twisted insulated pairs are stored prior to their use informing the cables. An equally, If not more important need forlsuch' identifymg means arises in the stranding process to enable the workmen and supervisors to' determine whether thetwisted pairs upon the spools whichhave been arranged upon the spindles of the stranding machines have the proper length of twist to produce the desired lay-up in the stranded cable. 7

In view of the fairly complex nature of the existing color code, of exchange cables, it was necessary to avoid the use of distinguishing marks which would add to the present complexity and might tend to cause confusion in manufacturing and installing exghange cables embodying the present color co e.

to provide a simple method for distinctively marking the insulation of one of the wires of a air having a redetermined length P sh that air from an-- of twlst to distingui other pair having the same co ore of insulation, but a different length of twist from the first mentioned air.

' This invention wil beclearly understood from the followin description when read in connection wit the attached drawing of which Figure 1 represents a pad of insulating pa er marke in a manner hereinafter descri ed which forms a part of the to result un- It is one of the objects of this invention.

invention; Fig. 2 represents a conductor to which such marked insulation has been applied; and Fig. 3 shows a pair of wires, one. of which bears the designating mark shown in Fig. 2. 1

In preparing the paper used in insulating the conductors of a telephone cable, it is customary to cut transversely or to slice a large roll of paper into a number of smaller rolls or pads, each of which is a flat, tightly coiled helix. Such a pad of paper,- which is in the nature of a long, coiled tape, is put upon an insulating machine of the type well known in the art, and the paper is drawn oii at a definite angle, while the pad revolves around theconductor to be insulated. This paper tape is placed upon the conductor in a way that the successive convolutions of paper tape overlap the preceding one, the amount of overlap being determined by various factors. This leaves uncovered one edge of the ape after it has been applied to the electrical conductor. By utilizlng this characteristic of the pa er insulated conductor, namely, the expose edge of the spiralled tape, it is practicable to clearly distin uish two insulated conductors, even though the color of the insulating material is the same upon both conductors.

My invention consists in placing upon one side of the pad before it is unrolled a coating of a distinctive color and in applying the paper tape to a conductor in such manner that the coated edge of the paper ta e is the one which is not covered up by t e overlapping of the successive convolutions of the tape. Such a marked conductor presents the appearance of having a colored thread s iralled over the insulatin material, whlch thread, however, is su ciently fine as not to cause confusion.

The first step in carrying out this invention will be clearly seen in Fig. 1, where the upper surface of the pad 1 has been colored in a distinctive manner. It is preferable that this color shall form only a coating upon the side of the pad, that is to say, that it shall not penetrate transversely through the pad in the direction shown by the arrow. Such penetration would tend to cause discoloration of the insulating paper and to increase the difficult in distinguishing the different wires in t e subsequent processes of manufacture and of in-' stalling the cables. The application to a conductor of the paper insulating tape of Fig.. 1 is clearly shown in Fig. 2 wherein the conductor 2 is insulated by means of the spiral wrapping of paper 3. The colored edge of the paper, represented by 4, may be made as light or as heavy as is demanded by the circumstances of each particular case. It is important, however, that in signaling cables, particularly telephone cables, the coloring matter shall not penetrate through no distinguishin the pad of insulating paper to such extent as to change the appearance of the color of the paper tape, because any material change in such colors tends towards the im airment of the splicing efliciency of such ca les.

Fig. 3 shows a pair of conductors in which this invention is employed. As will be readily seen, the insulation upon conductor 5 has a marked edge 6, which readily distinguishes the pair of wires with which it is associated from another pair of wires having paper insulation of the same colors as the first pair, but not having such designated marking thereon. If, for example, conductor 7 is insulated with blue paper and conductor 5 with white or grey paper, having the exposed edge of the insulation slightly blackened, such a pair of insulated conductors will be readily distinguishable from another blue-white or blue-grey pair in which the white or grey insulation bears mark such as is carried by the first mentioned pair. Thus, similarly colored pairs which have different lengths of twist may be readily. distinguished.

While the invention is not limited to any particular method for applying this colored lm or coating to a pad of insulating paper, it has been found practicable to do so by means of the ink roller of the ordinary printing press. Furthermore,'various ways may sug est themselves to those skilled in the art, ut it is desirable that the film or coating shall not penetrate .greatly in a transverse direction as represented by the arrow in Fig. 1.

The utility of this invention in the storerooms and in the factory where the pairs of wires are assembled in the form of cables, has already been referred to, but it also finds-use in the field during the installation and maintenance of such cables. Since the conductors of a pair having a shorter twist are longer than the conductors of a pair having a longer twist, it may be desirable in order to equalize the lengths of conductors in a cable, and thereby to equalize the loop resistances, to splice together adjacent sections of cable in such manner that the pairs having short twists in one section will be spliced to pairs in the next section having long twists. The presence of the distinguishing mark along the uncovered ,edge of the insulation of a conductor of one pair will enable the splicer to distin uish such pairs from the othersimilarl co ored pairs having a different len h o twist.

While this invention has een described as applied to paper insulation, it is not limited to this t e of insulation, but may be aplied to ot er suitable insulatin material. urthermore while mention has 11 made of a colored film or coating, it is to be understood that this does not mean that the colora ing material cannot and does not penetrate the fibre of the insulation to some extent. The invention covers the use of dyes or stainsapplied to the edge of the tape, even though such method may involve some penetratio'n through the fibre of the tape.

Althou h this invention has been disclosed as embodied in a particular form and arrangement of parts, it is to be understood that it is not so limited, but may be embodied in other forms without departing from the spirit and scope of the appended claims.

What is claimed is:

1. The method of placing a distinguishing mark on a tape intended for insulating electrical conductors, which consists in coiling the tape in a compact spiral and then applying coloring material to one face of the spiral, thereby marking the corresponding edge of the stri along its entire length.

2. As an article 0 manufacture, a circular pad of paper comprising a strip wound tightly iii the form of a flat helix having one edge thereof colored differently from the color of the paper constituting said pad. 3. As an article of manufacture, a pad consisting of a helix of insulating tape, one side of the said pad being distinctively colored to contrast with the rest of the tape.

4. As an article of manufacture, aninsulating tape having an edge distinctively colored to contrast with the rest of the tape.

5. As an article of manufacture, an insulating tape having both edges distinctively colored to contrast with the rest of the tape.

6. As an article of manufacture, an insulating tape having an edge distinctively colored to contrast with the rest of the tape,

the faces of the said tape being substantially unafie'cted by the edge coloring.

In testimony whereof, I have signed my name to this specification this 25th day of September 1922.

WILLIAM H. MARTIN. 

